EvE in Custom Scenarios

In the Setup Custom Scenario window, under You, you have "is AI:" and "MP Party:" options but the former is unavailable to choose.
Why would they leave it there if you can't choose it? Is there a way to unlock it?
I would like to see how the AI would behave if pitted against itself.

You have to have at least one human player in any match which is why the first AI option is greyed out.
You can uncheck the MP Party option to play as monsters but you cannot pit two AI's against each other even though that would be fun.